/*
 * Anything: A flexible and easy to use data structure that combines the 
 * characteristics of a list and a hashmap into one data structure.
 * 
 * Based on a paper by Peter Sommerlad and Marcel Rueedi on 
 * 'Do-it-yourself reflection' entered at EuroPLOP 1998.
 * 
 * This library was written completely from scratch and is based only 
 * in spirit on the original Java Anything implementation written by 
 * Andre Weinand/Marcel Rueedi in 1997/99 and enhanced by Stefan Tramm 
 * in 2006.
 * 
 * Copyright (c) 2008 Thomas Marti and others. All rights reserved.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package any.functor.impl.func;

import java.math.BigDecimal;

import any.ImmutableAny;
import any.functor.interfaces.NumberDefaultableFunction;

/**
 * 
 * 
 * @param <TO> Type of the function output, must extend {@link Number}.
 * @param <T>  Implementation type of the function
 */
abstract class BaseAsNumberFunction<TO extends Number, T extends BaseAsNumberFunction<TO, T>> 
  extends BaseDefaultableFunction<TO, Number, T> 
  implements NumberDefaultableFunction<TO> {
	
	public BaseAsNumberFunction(Class<TO> type) {
		super(type);
	}
	
	public BaseAsNumberFunction(Class<TO> type, String description) {
		super(type, description);
	}
	
	@Override
	protected TO applyWithDefault(ImmutableAny from, Number defaultValue) {
		BigDecimal asBigDecimal = from.asBigDecimal(defaultValue);
		try {
			return (asBigDecimal != null ? convertNumber(asBigDecimal) : null);
		} catch (ArithmeticException e) {
			throw new IllegalStateException(e);
		}
	}
	
	@Override
	protected TO applyWithoutDefault(ImmutableAny from) throws IllegalStateException {
		BigDecimal asBigDecimal = from.asBigDecimal(null);
		if (asBigDecimal == null) {
			throw new IllegalStateException(from + " cannot be represented as BigDecimal!");
		}
		
		try {
			return convertNumber(asBigDecimal);
		} catch (ArithmeticException e) {
			throw new IllegalStateException(e);
		}
	}
	
	protected abstract TO convertNumber(BigDecimal value) throws ArithmeticException;

	@Override
	protected String toStringPrefix() {
		return description + (exact ? "Exact" : "");
	}
	
}
